Metal additive manufacturing methods enable manufacturers to create end-use metal articles that often outperform those produced with traditional machining and casting techniques. These methods may also enable the manufacture of parts that cannot otherwise be made by conventional methods. And they may provide the benefit of significantly reduced manufacturing costs. Once those articles are installed for end-use, they contribute to cost savings because of one or more of light weight, high strength, and precise fit. In the context of turbines, particularly gas or steam turbines, a variety of components or portions thereof may be additively manufactured, including, for example: turbine component selected from the group consisting of a hot gas path component, a shroud, a bucket (blade), a nozzle (vane), and a seal. In some particular examples, combustor components and hot gas path components may be manufactured by additive processes to enable forming of complex geometries without the requirement for extensive post processing, including, but not limited to, nozzle bars, micromixer plenums, combustion flex tips and microchannel cooled shrouds.
Though there are many benefits to be realized with additive manufacturing, in contrast to some conventional manufacturing techniques, articles that are additively manufactured may have surface features that are less refined or less smooth. Some artifacts of the additive manufacturing process include surfaces that are rough and irregular, and include or may be prone to cracks, gaps and other defects. Thus, while many advantages can be achieved through additive manufacturing, a drawback is that the resultant rough surfaces can adversely affect performance both in terms of the flow dynamics and leakage, and in some cases the parts cannot be used due to compromised flow integrity due to gaps and cracks. This aspect of the manufacturing process necessitates post processing procedures which can at least in part obviate some benefits related to cost, and can also adversely affect the preservation of fine structures and complex geometries of the manufactured article.
Accordingly, there is a need in the art for post processing treatments to reduce the surface roughness without appreciably altering the structural features of the additively manufactured article.